The present invention relates to a display device and particularly to a display device having a wide viewing angle and enhanced luminance by employing a deep blue backlight lamp and a phosphor layer stimulated by the lamp.
An optoelectronic display device is a light receiving display device such as an LCD device or a PLZT device. The light receiving display device has a basic structure in which liquid crystal material or PLZT optoelectronic material is sandwiched between longitudinal and latitudinal electrodes. An analyzer is on the front side and a polarizer is on the back side. In order to obtain full color display using such a device, a white light source (backlight) on the back side and red, green, blue color filters arranged on each pixel on the front side are provided to drive the optoelectronic material.
The structure of this type of optoelectronic display device is illustrated in detail with reference to the attached FIG. 1. In this figure, a backlight 1 emits white light from the back side, a polarizer 2 selects only light having a prescribed direction among the emitted backlight, and an analyzer 6 receives the selected light. Between the polarizer 2 and analyzer 6, an optoelectronic material 4 being sandwiched by latitudinal and longitudinal electrodes 3 and 5 is provided. On the front side, a pattern of color filter 7 is formed on a substrate 10. In the other basic system, the pattern of color filter 7 can be located between the electrode 5 and the analyzer 6. According to the previous systems, the location of the color filter can be subtle.
A liquid crystal display device employing TN (twisted nematic), STN (super twisted nematic) or ferroelectic liquid crystal as an optoelectronic material, which constitutes the main current draw of the liquid crystal display device, utilizes an optoelectronic effect by which a molecular orientation of liquid crystal material changes based on an applied electrical field or heat. Since such a device operates at low voltage and consumes a little electric power, and the display pattern dimensions can be freely designed, this device has a wide range of applications, including flat panel displays such as those for use in a liquid crystal color television, as well as, laptop computers, digital displays and digital watches.
Another optoelectronic material, PLZT, is a transparent ferroelectric material which is represented by the general formula of (Pb.sub.1-x La.sub.x)(Zr.sub.1-y Ti.sub.y).sub.1-x/4 O.sub.3 (0&lt;x.ltoreq.0.3, 0.ltoreq.y.ltoreq.1.0). According to the composition ratio of the material, this shows various electric and optic characteristics. Recently, research and development work has been widely carried out on various display devices (photo-modulators, photo-switches, photo-shutter, etc.) using this material.
However, since the above-mentioned devices employ a polarizer, luminance is low due to the poor light utilization efficiency. Moreover, since the light from the backlight, i.e., white light, should pass through the PLZT or liquid crystal material, the electrodes, polarizer and a color filter, the light intensity is severely weakened compared with the originally emitted white light. Also, since the LC or PLZT shutter limits the traveling angle of backlight, the light via a light shutter results in a very narrow viewing angle.